Thanks for the information. Yes, indeed I'm thinking of buying a
machine and most likely the OS will be linux.
All I can tell is that running SAGE on a Windows machine (via
VMware Player) is pretty slow. The CPU on my laptop is an Intel Core 2
Duo U7600 and
timeit('factorial(10^6)') shows that it takes 11.3s to run... (compare
to William's Xeon machine, 2s). I almost thought the system hanged
(took a min to run timeit).
On Nov 29, 12:09 pm, Robert Bradshaw <[EMAIL PROTECTED]>
wrote:
> On Nov 29, 2008, at 11:47 AM, mabshoff wrote:
>
>
>
> > On Nov 29, 11:37 am, Robert Bradshaw <[EMAIL PROTECTED]>
> > wrote:
> >>> On Nov 29, 2008, at 07:35 , pong wrote:
>
> >>>> Hi,
>
> >>>> I wonder if SAGE is optimized for multi-core CUPs (people
> >>>> told me
> >>>> that many programs don't).
>
> >>> This is not an easy question to answer. Sage is built from many
> >>> components that were not specifically designed with Sage or
> >>> multiprocessor issues in mind.
>
> >>> Most programmers and algorithm designers, even today, don't think in
> >>> terms of a "tight-coupled" multiprocessor implementation. Some do
> >>> think of loose coupling. The distinction is the amount of
> >>> information
> >>> needed to be shared between the "cooperating processes". For
> >>> example,
> >>> Michael and a host of others worked hard to get the Sage build to
> >>> take
> >>> advantage of multiple processors. This was not easy, because the
> >>> components come from many sources, and their build process was not
> >>> designed to take advantage of these systems, but it was feasible
> >>> because the different components need very little information
> >>> from the
> >>> other components (basically, 'make' has to know what the
> >>> dependencies
> >>> are, so it can find independent builds to run at the same time).
>
> >>> The software that makes up Sage is another matter entirely. Code
> >>> does
> >>> not automatically work optimally on a multiprocessor system (whether
> >>> multi-core or multiple single-core chips). That effort takes a
> >>> lot of
> >>> work.
>
> >> One important component of Sage, ATLAS, does take advantage of
> >> multiple processors, which is directly taken advantage of in all the
> >> linear algebra (numeric and exact).
>
> > No, it doesn't per default in Sage on non-OSX since we only build a
> > single threaded ATLAS there. Due to the Accelerate Framework on OSX
> > large problems that employ BLAS do use multiple cores automatically.
> > The Accelerate Framework contains code derived from ATLAS for the BLAS
> > portion, but that code was never given back by Apple.
>
> I stand corrected--most of my experience is on OSX where it is easy
> to see both cores being utilized. I didn't know this wasn't the case
> elsewhere (yet).
>
> > I have build Sage versions with a multi CPU ATLAS per default, but
> > that code never made it into upstream. I have been contemplating what
> > to do and I do have the following BLAS plan:
>
> [...]
>
> > Thoughts?
>
> Sounds good to me, but I have not experience in the area.
>
> - Robert
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